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首页> 外文期刊>Journal of the Atmospheric Sciences >Implications of microphysics for cloud-radiation parameterizations: Lessons from TOGA COARE
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Implications of microphysics for cloud-radiation parameterizations: Lessons from TOGA COARE

机译：微物理学对云辐射参数化的影响：TOGA COARE的经验教训

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A single-column model (SCM) and observational data collected during TOGA COARE were used to investigate the sensitivity of model-produced cloud properties and radiative fluxes to the representation of cloud microphysics in the cloud-radiation parameterizations. Four 78-day SCM numerical experiments were conducted for the atmospheric column overlying the COARE Intensive Flux Array. Each SCM experiment used a different cloud-radiation parameterization with a different representation of cloud microphysics. All the SCM experiments successfully reproduced most of the observed temporal variability in precipitation, cloud fraction, shortwave and longwave cloud forcing, and downwelling surface shortwave flux. The magnitude and temporal variability of the downward surface longwave flux was overestimated by all the SCM experiments. This bins is probably due to clouds forming too low in the model atmosphere. Time-averaged model results were used to examine the sensitivity of model performance to the differences between the four cloud-radiation parameterization packages. The SCM versions that calculated cloud amount as a function of cloud liquid water, instead of using a relative humidity-based cloud scheme, produced smaller amounts of both low and deep convective clouds. Additionally, larger high (cirrus) cloud emissivities were obtained with interactive cloud liquid water schemes than with the relative humidity-based scheme. Surprisingly. calculating cloud optical properties as a function of cloud liquid water amount, instead of parameterizing them based on temperature, humidity, and pressure, resulted in relatively little change in radiative fluxes. However. model radiative fluxes were sensitive to the specification of the effective cloud droplet radius. Optically thicker low clouds and optically thinner high clouds were produced when an interactive effective cloud droplet radius scheme was used instead of specifying a constant value. Comparison of model results to both surface and satellite observations revealed that model experiments that calculated cloud properties as a function of cloud liquid water produced more realistic cloud amounts and radiative fluxes. The most realistic vertical distribution of clouds was obtained from the SCM experiment that included the most complete representation of cloud microphysics. Due to the limitations of SCMs. the above conclusions are model dependent and need to be tested in a general circulation model. [References: 54]
机译：在TOGA COARE期间收集的单列模型（SCM）和观测数据用于研究在云辐射参数化中模型生成的云特性和辐射通量对云微物理学表示的敏感性。对覆盖COARE密集通量阵列的大气柱进行了四个78天的SCM数值实验。每个SCM实验都使用不同的云辐射参数化以及不同的云微观物理表示。所有SCM实验都成功地再现了观测到的大部分时间变化，包括降水，云量，短波和长波云强迫以及下表面地表短波通量。所有SCM实验都高估了下表面长波通量的大小和时间变化。该垃圾箱可能是由于在模型大气中形成的云太低所致。时间平均模型结果用于检查模型性能对四个云辐射参数化程序包之间差异的敏感性。 SCM版本将云量作为云液态水的函数进行计算，而不是使用基于湿度的相对云方案，而是生成了较少量的低层和深层对流云。此外，与基于相对湿度的方案相比，交互式云液态水方案可获得更高的高（卷云）发射率。出奇。根据云的液态水量计算云的光学特性，而不是根据温度，湿度和压力对其进行参数化设置，导致辐射通量的变化相对较小。然而。模型的辐射通量对有效云滴半径的规格很敏感。当使用交互式有效云滴半径方案而不指定常量值时，会生成光学上较厚的低云和光学上较薄的高云。将模型结果与地面和卫星观测结果进行比较后发现，将云性质作为云液态水的函数进行计算的模型实验会产生更逼真的云量和辐射通量。从SCM实验获得了最真实的云垂直分布，其中包括对云微物理学最完整的表示。由于单片机的限制。以上结论与模型有关，需要在通用循环模型中进行检验。 [参考：54]

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